src/compiler-rt/test/dfsan/write_callback.c

   1 // RUN: %clang_dfsan                         %s -o %t && %run %t | FileCheck %s
   2 // RUN: %clang_dfsan  -mllvm -dfsan-args-abi %s -o %t && %run %t | FileCheck %s
   3
   4 // Tests that the custom implementation of write() does writes with or without
   5 // a callback set using dfsan_set_write_callback().
   6 // REQUIRES: stable-runtime
   7
   8 #include <sanitizer/dfsan_interface.h>
   9
  10 #include <assert.h>
  11 #include <fcntl.h>
  12 #include <stdio.h>
  13 #include <string.h>
  14 #include <unistd.h>
  15
  16 // Check write callback arguments by having the callback store them in
  17 // the following variables:
  18 static int last_callback_arg_fd;
  19 static const void *last_callback_arg_buf;
  20 static size_t last_callback_arg_count;
  21
  22 // Allow tests to check the number of callbacks made by incrementing
  23 // this count.  When callbacks are verified, the count is reset.
  24 static int count_unverified_callbacks = 0;
  25
  26 // This callbact will be installed using dfsan_set_write_callback()
  27 // in tests below.
  28 static void write_callback(int fd, const void *buf, size_t count) {
  29   // Do not do anything in this function that might call write().
  30   count_unverified_callbacks++;
  31
  32   last_callback_arg_fd = fd;
  33   last_callback_arg_buf = buf;
  34   last_callback_arg_count = count;
  35 }
  36
  37 static void write_string_to_stdout(char *string) {
  38   char *cur = string;
  39   int bytes_left = strlen(string);
  40   while (bytes_left > 0) {
  41     int res = write(fileno(stdout), cur, bytes_left);
  42     assert (res >= 0);
  43     cur += res;
  44     bytes_left -= res;
  45   }
  46 }
  47
  48 static void test_can_write_without_callback() {
  49   dfsan_set_write_callback(NULL);
  50   count_unverified_callbacks = 0;
  51
  52   char aString[] = "Test that writes work without callback.\n";
  53   // CHECK: Test that writes work without callback.
  54   write_string_to_stdout(aString);
  55
  56   assert(count_unverified_callbacks == 0);
  57 }
  58
  59 static void test_can_write_with_callback() {
  60   dfsan_set_write_callback(write_callback);
  61
  62   count_unverified_callbacks = 0;
  63
  64   char stringWithCallback[] = "Test that writes work with callback.\n";
  65   // CHECK: Test that writes work with callback.
  66   write_string_to_stdout(stringWithCallback);
  67
  68   // Data was written, so at least one call to write() was made.
  69   // Because a write may not process all the bytes it is passed, there
  70   // may have been several calls to write().
  71   assert(count_unverified_callbacks > 0);
  72   count_unverified_callbacks = 0;
  73
  74   dfsan_set_write_callback(NULL);
  75
  76   char stringWithoutCallback[] = "Writes work after the callback is removed.\n";
  77   // CHECK: Writes work after the callback is removed.
  78   write_string_to_stdout(stringWithoutCallback);
  79   assert(count_unverified_callbacks == 0);
  80 }
  81
  82 static void test_failing_write_runs_callback() {
  83   // Open /dev/null in read-only mode.  Calling write() on fd will fail.
  84   int fd = open("/dev/null", O_RDONLY);
  85   assert(fd != -1);
  86
  87   // Install a callback.
  88   dfsan_set_write_callback(write_callback);
  89
  90   // Write to the read-only file handle.  The write will fail, but the callback
  91   // should still be invoked.
  92   char aString[] = "This text will fail to be written.\n";
  93   int len = strlen(aString);
  94   int write_result = write(fd, aString, len);
  95   assert(write_result == -1);
  96
  97   assert(count_unverified_callbacks == 1);
  98   count_unverified_callbacks = 0;
  99
 100   assert(fd == last_callback_arg_fd);
 101   assert(aString == last_callback_arg_buf);
 102   assert(len == last_callback_arg_count);
 103
 104   close(fd);
 105 }
 106
 107 int main(int argc, char* argv[]) {
 108   test_can_write_without_callback();
 109   test_can_write_with_callback();
 110   test_failing_write_runs_callback();
 111 }